Malatesta’s Carnival of Blood (1972)

Vena Norris and her parents get jobs at Mr. Malatesta's carnival running a midway games booth. But they are really part of the traveling show circuit under incredibly false pretenses. Vena's brother disappeared one night while visiting the evil attraction, and his kinfolk are convinced they can discover what happened to him by scamming teenagers out of their allowances. What they do learn is pretty strange indeed.